Performance evaluation and optimization of a phase-change material -integrated thermochromic glazing for office buildings

Predicting the date of harvest of vining peas by means of air and soil temperature sums and node countings

Installing photo-voltaic (PV) panels on building façades is a growing tendency that helps to achieve both newly built and renovated nearly zero energy buildings. A novel approach to building active facades is to use a phase change material (PCM) behind the flexible PV. The PCM stabilises the PV’s temperature which can lead to an increase in energy production and cuts down the temperature peaks to avoid damage. In this study, the thermal performance of an En-ActivETICS wall was modelled in three different locations across Europe. The model was validated against on-site temperature measurements. The efficiency of the PV was calculated and an optimal PCM thickness and melting temperature were selected. The results show that annual energy production of the PV panel could increase between 2% (in Lodz) to 5% (in Madrid) using a 40mm-thick PCM. The optimal PCM melting temperatures for a certain climate should be chosen as 0 to 10 degrees below maximum air temperature in summer. The maximum peak PV temperatures could be reduced by ca. 20 K (from ∼90 to ∼70°C). Reasonable way to fix the stainless steel casing to the wall would be with four stainless steel anchor bolts – that gives 78% or 93% efficiency in case of EPS or PIR thermal insulation, respectively.

A 70-year history of precipitation δ18O record has been retrieved using an ice core drilled from a plat portion of the firn area in the Guoqu Glacier (33°34′37.8″ N, 91°10′35.3″ E, 5720 m a.s.l.) on Mt. Geladaindong (the source region of Yangtze River) during October and November, 2005. Based on the seasonality of δ18O records and the significant positive relationships between monsoon/non-monsoon δ18O values and summer/spring air temperature from the nearby meteorological stations, the history of summer and spring air temperature have been reconstructed for the last 70 years. The results show that both summer and spring air temperature variations present similar trends during the last 70 years. Regression analysis indicates that the slope of the temperature-δ18O relationship is 1.3°C/‰ for non-monsoon δ18O values and spring air temperature, and 0.4°C/‰ for monsoon δ18O values and summer air temperature. Variation of air temperature recorded in the ice core is consistent with that in the Northern Hemisphere (NH), however, the warming trend in the Geladaindong region is more intense than that in the NH, reflecting a higher sensitivity to global warming in the high elevation regions. In addition, warming trend is greater in spring than in summer.

The application of a lightweight building is limited because its indoor temperature is highly affected by the outdoor environment due to the low thermal inertia of the lightweight envelope. In order to improve the thermal performance, this study focuses on lightweight buildings integrated with phase change materials. EnergyPlus software with building model validated by experimental data is used to analyze the thermal performance improvement of lightweight buildings by integrating with phase change materials under typical weather conditions in five climate zones in China. The results show that phase change materials can reduce temperature fluctuations through improving the heat stability of the lightweight envelope. Phase change materials can effectively improve the indoor thermal environment throughout the whole year in a temperate zone. Also, phase change materials can improve the indoor thermal environment of lightweight buildings significantly in the transition seasons, but it also reduces the hours of the indoor air temperature within the range 18°C (64.4°F) to 26°C (78.8°F) during cold winters and hot summers. For the lightweight buildings with air conditioning, due to the addition phase change material, heating loads can be reduced by 40–70%, while cooling loads increase slightly in the summers with the higher air temperature.

Building envelopes incorporating phase change materials (PCMs) can contribute to reducing the energy consumption of buildings and enhance indoor thermal environment comfort. In this study, two building models were developed in EnergyPlus to explore the applicability of using PCMs in different climate zones. Six significantly different cities from five climate zones in China have been investigated. The simulation results reflected that for climates with small fluctuation weather conditions, PCMs with appreciate transition temperature TR can contribute to positive influences on energy saving. For example, in Guangzhou, PCMs with TR of near 26oC and 22oC contribute to the highest energy-saving rates of 12.0% and 12.4%, for external and internal PCMs addition. And the ideal transition temperature for each climates is subjected to its own outdoor comprehensive temperatures and its indoor set temperature, for external and internal PCMs addition, respectively. For other climates with the big fluctuation weather condition, PCMs' latent heat function to the energy savings is not significant.

Glass curtain walls (GCWs) have become prevalent in office buildings, owing to their lightweight and modular characteristics. However, their lower thermal resistance, compared to opaque walls, results in increased energy consumption. Incorporating phase-change materials (PCMs) provides a viable solution through which to address the susceptibility of GCWs to external conditions, thus enhancing thermal performance and mitigating energy concerns. This study delves into the influences of the glazing solar heat gain coefficient (SHGC), the glazing heat transfer coefficient (U-value), and PCM thickness on the energy performance of buildings. Using Design Builder (DB) software version 6.1.0.006, a multi-story office building was simulated in different climatic zones in China, covering the climatic characteristics of severe cold, cold, hot summer and warm winter, cold summer and winter, and mild regions. The simulation results quantitatively elucidated the effects of the glazing parameters and the number of PCMs on thermal regulation and energy consumption. A sensitivity analysis identified the glazing SHGC as the most influential factor in energy consumption. Additionally, by employing Response Surface Methodology (RSM), the researchers aimed to achieve a balance between minimal building energy consumption and economic cost, ultimately determining an optimal design solution. The results demonstrated significant energy savings, ranging from 20.16% to 81.18%, accompanied by economic savings, ranging from 15.78% to 79.54%, across distinct climate zones in China.

Numerical analysis on the thermal performance of PCM-integrated thermochromic glazing systems

As the impact of climate change intensifies, meeting the energy demand of buildings in China’s cold regions is becoming increasingly challenging, particularly in terms of cooling energy consumption. The effectiveness of integrating phase change material (PCM) into building envelopes for energy saving in China’s cold regions is unclear. The aim of this study is to assess the effectiveness of PCM integration in building enclosures for energy efficiency in these regions. The research monitored and recorded indoor temperature data from typical residential cases from May to September. This measured data was then used to validate the accuracy of EnergyPlus22-1 software simulation models. Subsequently, the calibrated model was utilized to conduct a comparative analysis on the effects of PCM on indoor temperatures and cooling energy consumption across these regions. The results of these comparative analyses indicated that PCM can alleviate indoor overheating to varying degrees in severe cold regions of China. Focusing on north-facing bedrooms, applying PCMs reduced the duration of overheating in non-air-conditioned buildings in severe cold regions of China by 136 h (Yichun), 340 h (Harbin), 356 h (Shenyang), and 153 h (Dalian). In terms of cooling energy consumption, the energy saved by applying PCMs ranged from 1.48 to 13.83 kWh/m2. These results emphasize that the performance of PCM varies with climate change, with the most significant energy-saving effects observed in severe cold regions. In north-facing bedrooms in Harbin, the energy-saving rate was as high as 60.30%. Based on these results, the study offers guidance and recommendations for feasible passive energy-saving strategies for buildings in severe cold and cold regions of China in the face of climate change. Additionally, it provides practical guidance for applying PCMs in different climatic zones in China.

Multi-objective optimization of thermochromic glazing properties to enhance building energy performance

Research on Indoor Thermal Environment Improvement of Lightweight Building Integrated with Phase Change Material under Different Climate Conditions

Concerning the distribution of the air temperature in summer in Miyagi prefecture, the author found many exmaples of the pattern as is shown in the Figure, with lower temperature in the coastal region. And the temperature gradient form the coast toward the inland was investigated in relation to the diurnal changes. The author observed diurnal variation of air temperature at several places in summer 1964. In the coastal region, the air temperature first rises by a few degrees, then remains constant after the breeze begins to blow. This temperature continues as long as the sea breeze blows. Therefore, the air temperature becomes higher according to the distance from the coast, because the sea breeze is later to advance toward inland.Thus, the gradient twoards inland mentioned above can be understood from the view-point of the regional difference of diurnal variation of the air temperature.

The thermal environment in residential areas is directly related to the living quality of residents. Therefore, it is important to understand thermal heterogeneity and ways to regulate temperature in residential neighborhoods. We investigated the spatial heterogeneity and temporal dynamics of air temperatures in 20 residential neighborhoods within the 5th ring road of Beijing, China. We further explored how the variations in air temperature were related to the patterns of the surrounding greenspace at different scales. We found that: (1) large air temperature differences existed among residential neighborhoods, with hourly maximum differences in air temperature reaching 5.30 °C on hot summer days; (2) not only the percentage but also the spatial configuration (e.g., edge density) of greenspace affected the local air temperature; and (3) the effects of spatial greenspace patterns on air temperature were scale dependent and varied by season. For example, increasing the proportion of greenspace in surrounding areas within a 100-m radius and increasing the edge density within radii from 500 to 1000 m could lower air temperatures in summer but not affect air temperatures in winter. In addition, decreasing the edge density of greenspaces within a 100-m radius of the surrounding areas would lead to an increase in air temperature in winter but not affect the air temperature in summer. These results extend our understanding of thermal environments and their relationships with greenspace patterns at the microscale (i.e., residential neighborhoods). They also provide useful information for urban planners to optimize greenspace patterns under better thermal conditions at the neighborhood scale.

The results of the study of the dependence of the grain quality of soft spring wheat (Tríticum aestívum L.) on the main agroclimatic resources in the territory of the Republic of Bashkortostan are presented. Field experiments were carried out in different geographical locations of the republic according to the methodology of the State Variety Trial. Laboratory analyses of grain quality were carried out according to the methodology set forth in the State Standards. It has been established that the quality of soft spring wheat grain in the Republic of Bashkortostan largely depends on agroclimatic resources. In recent years, there has been a manifestation of global climate change on the territory of the republic. The amount of gluten in the grain depends to a large extent on the change in the average daily air temperature in June (r = 0.741) and to a slight extent on the average daily temperature in July (r = 0.359). The degree of dependence of gluten content increases significantly with an increase in the sum of air temperatures during the active vegetation of spring wheat (r = 0.812). The dependence of gluten content on the sum of temperatures in June and July is straightforward, and an increase in heat resources during the vegetation period of spring wheat plants by 10 °C contributes to an increase in the gluten content in grain by 0.73 %. Heat resources have a comparatively weak effect on other indicators of wheat grain quality. The correlation coefficient between gluten content and precipitation in July was 0.764. An increase in precipitation in July by 10 mm leads to a decrease in the gluten content in the grain of spring soft wheat by 0.49 %. High moisture availability also leads to the formation of soft spring wheat grain with low vitreousness (r = –0.547) and natural weight (r = –0.521). Moisture resources had a small effect on the gluten deformation index (r = 0.227). Precipitation in June has a weak effect on the quality indicators of spring soft wheat grain. The correlation coefficients between the sum of precipitation in June and the quality indicators were positive and ranged from 0.223 to 0.341

The article presents a spatio-temporal assessment of the changes in meteorological parameters characterizing the temperature regime of the Trans-Baikal Territory during the period of modern warming, which began in the mid-1970s. We analyzed both the average annual and average seasonal air temperatures as well as important indicators of heat supply such as stable periods with different air temperatures, a period without frosts, their beginning and end, the sum of air temperatures above 5 and 10°C. The distribution of the considered characteristics and their changes by geo-administrative districts of the region is shown. For the study period, along with an increase in the average annual air temperature, mainly associated with intensive growth in the spring months, there is also noted an increase in the duration of stable periods above certain air temperatures and a period without frosts. The dates of their onset began to be noted earlier in the spring and later in the autumn. The sums of temperatures above 5 and 10°C have also increased. The last decade has been characterized by the most intensive rise in air temperatures, especially in the winter months. As a result, the growth rate of most of the other parameters considered in the paper, which mainly characterize the heat supply of the warm period, has been declining in recent years. The results obtained can be used as a scientific basis for planning sectoral and regional strategies for adaptation to modern climate change.

Performance study on different location of double layers SSPCM wallboard in office building